This invention relates to motor vehicle wheel arrangements, especially for passenger motor vehicles, in which a central part supporting the wheel rim is removably mounted on the wheel hub by a central nut.
Conventional wheels for motor vehicles such as passenger motor vehicles include spoke wheels, cast wheels and so-called disk wheels. At present, disk wheels with disks pressed from sheet steel, also known as dished wheels, are preferred, especially for mass-production vehicles, because of their high dependability as well as their more favorable manufacturing cost compared to cast and spoke wheels.
In the disk wheel described in German Offenlegungsschrift No. 30 27 191, four or five, but in any case at least three, bolt holes are provided in the central portion of the disk for attachment of the disk wheel to the hub. The bolt holes are arranged in a circle and are equally spaced, the number and diameter of the holes depending upon the wheel load and other design considerations. Mounting of the disk to the hub is accomplished either by using fastening screws extending through the bolt holes into the hub with their heads in contact with the disk or by fastening nuts screwed onto studs fixedly mounted on the hub and extending through the disk holes so that the fastening screws or nuts clamp the wheel disk to the hub.
Usually, the wheel disk is depressed in a marginal zone around each of the bolt holes in the manner of a funnel to receive a correspondingly-shaped retaining screw head or nut. As a result, approximately truncated cone-like or partially spherical portions of the wheel disk, flaring toward the hub, are located between the screw and the hub, acting on the screw connection in the manner of a spring washer, i.e., undergoing a considerable elastic deformation when the wheel disk is mounted onto the hub.
Centering of the wheel disk on the hub is commonly effected in such disk wheels by the cooperation of the screw heads or nuts which are formed with spherical or conical bearing surfaces and the correspondingly spherical or conical conformation of the marginal zone around the bolt holes.
In order to remove and replace the wheels more quickly when changing tires, for example, it is known, especially in the case of sport and racing vehicles, to provide a wheel which is removably connected to its hub with only one screw connection, using a central nut screwed onto the trunnion.
German Offenlegungsschrift No. 28 18 512 discloses a motor vehicle wheel arrangement of this kind. In that arrangement, a cast wheel has a central portion supporting the wheel rim which includes a compact central bushing extending over a substantial portion of the width of the wheel and having a central bore of multiply-stepped diameter to be received on a correspondingly-stepped trunnion. A central nut screwed on the threaded free end of the trunnion has a portion facing the hub which extends into the central bore. The nut is approximately centrally positioned and has a radial shoulder beveled on the side facing the hub which cooperates with a mating externally-beveled annular zone of the central bushing to center the wheel on the trunnion and also provide an axial tension between the wheel and the hub. The trunnion and the wheel, or its central bushing, are held in angularly-fixed relation by engaged sinusoidally-shaped gear teeth in the central bore of the hub and in the portion of the trunnion facing the hub.